When a frame is transmitted over a network, currently, a bridge device is used which determines a transmission port for the frame and forwards it, on the basis of information regarding the data link layer. In order to fulfill this function, a bridge device has an updatable MAC (media access control) address table in which MAC addresses of other communication devices are related to corresponding port identifiers by, for example, an interface (IF) card. By referring to this MAC address table, the bridge device determines whether to forward or register a received frame, or selects a destination thereof when forwarding the frame. The bridge device mainly accesses the MAC address table when performing the following four processes: (A) the retrieval of a MAC destination address (MAC DA) upon transmission of a frame; (B) the retrieval of a MAC source address (MAC SA) upon reception of a frame; (C) the MAC learning (the registration of frame information); and (D) aging (the deletion of frame information). Hereinafter, the processes (A) to (D) are referred to as “access types (A) to (D)”, respectively.
Japanese Laid-open Patent Publication No. 11-68818 is an example of the related art.